Arrangement for a steam-heated autoclave

ABSTRACT

A steam operated autoclave is disclosed having a circulating steam phase, a steam producing water container, a double cleading surrounding the interior of the autoclave and valves in the conduits between the different parts of the autoclave and its accessories for selective operation of first and second heat elements arranged in said double cleading and the water container for obtaining an improved efficiency of such autoclaves by automatic preheating of the double cleading before each sterilization.

United States Patent 1 Linder Nov. 20, 1973 ARRANGEMENT FOR A STEAM-HEATED AUTOCLAVE [76] Inventor: Fritz Linder, Skarham, Sweden [22] Filed: July 12, 1971 211 App]. No.2 161,760

[30] Foreign Application Priority Data 3,298,776 1/1967 Beecher 21/103 X 3,338,663 8/1967 Beecher et a1... 21, 94 X 3,443,884 5/1969 Linder 21/104 X 3,481,692 12/1969 Linder 21/94 Primary Examiner-Barry S. Richman AttameyAlbert M. Parker et a1.

[5 7] ABSTRACT A steam operated autoclave is disclosed having a circulating steam phase, a steam producing water container, a double cleading surrounding the interior of the autoclave and valves in the conduits between the different parts of the autoclave and its accessories for selective operation of first and second heat elements arranged in said double cleading and the water container for obtaining an improved efficiency of such autoclaves by automatic preheating of the double cleading before each sterilization.

4 Claims, 1 Drawing Figure PATENTED NOV 20 1975 ARRANGEMENT FOR A STEAM-HEATED AUTOCLAVE This invention relates to an arrangement for a steamheated autoclave ,for improving the efficiency of such autoclaves during sterilization. More particularly, this invention relates to steam-heated autoclaves having at least a partially circulating steam phase, the steam being generated in a water container located exteriorly of the autoclave and being connected to a water storage means.

The best sterilization result is obtained when the temperature of the walls surrounding the interior of the autoclave has been substantially adjusted to the same,

temperature as the sterilizing temperature. Various constructions of autoclaves have therefore already been suggested with double sheaths or a double clead ing intended to be filled with steam for producing said temperature in the walls. Known arrangements are, however, expensive because of their complicated construction, particularly in view of the welding operations required for the autoclave vessel and the extremely complicated valve system necessary and it has therefore been impossible to use these known constructions to a great extent.

An important object of this invention is to provide a new and improved sterilization apparatus with improved efficiency.

Another object of this invention is to provide a new and improved sterilization apparatus in which the walls of the interior of the autoclave are automatically preheated immediately before or after each sterilization.

This invention creates an arrangement which'accomplishes all the aforementioned objects by an ingenious co-ordination of all the required measures.

According to the invention there is provided a steam operated sterilization system having a circulating steam phase comprising an autoclave having an interior heating space therein; a water container located exteriorly of the autoclave for producing steam and connected to communicate with the interior of the autoclave; a water storage means connected to the water container; a first heating means for heating cleading at least partly surrounding the autoclave; a second heating means for producing steam in the water container; means for selective operation of said first and second heating means before, during or after a sterilization cycle, whereby the first heating means is operated immediately before and after sterilization of articles in the autoclave and the second heating means is operated only during sterilization.

This arrangement enables the autoclave chamber to be quickly heated and the heat to be retained in the cleading around the autoclave during the actual sterilization cycle. This preheating following each sterilization can also be used to dry sterilized objects before they are taken out of the autoclave.

According to a suitable embodiment of the invention the double cleading is provided with heating elements regulated by a thermostat.

The steam is generated in a water container located exteriorly of the autoclave. The water container is connected to a water tank and the air forced out of the autoclave is gradually removed from the flow of steam by means of a known steam trap. The present construction comprises a combination of a first heating means for heating the double cleading surrounding the autoclave chamber and a second heating means for producing steam in the water container and switching means to alternately operate said first or said second heating means before and after the sterilization cycle, so that the first heating means is operating immediately before and after the sterilization cycle whereas the second heating means is operating only during the actual sterilization cycle. This alternative switching between the heating means may suitably be effected by means of a timer.

Further objects of the invention and further details comprised by it are explained in the following example of practical execution.

In the drawing an autoclave is designated by the reference numeral 1, the autoclave being surrounded by a double cleading 2 in the form of a metal block which can be heated by a heating means 3. The heating means 3 cooperates with a thermostat 4 which is preferably set at a temperature corresponding to the sterilization temperature.

The steam is generated in a water container 11 arranged outside the autoclave l and having a heating means 15 regulated by a thermostat 14. The water container 11 is connected by way ofa steam conduit 13 to a steam inlet 7 opening into the upper part of the autoclave chamber. Between said inlet conduit 7 and the feeding conduit 13 there is a branch conduit 12 which opens into the water container 1 1 and is intended to return excess water to the water container 11.

An outlet conduit 5 leads from the bottom of the autoclave chamber and this is connected by way of a three-way valve 17 and pertaining return conduit 10, to the water container 11. The return conduit 10 opens into the upper part of the water container 11. Of the three outlets of the three-way valve 17, therefore, a first outlet 17Ais connected to the outlet conduit 5, a second outlet 17B to the return conduit 10 and a third outlet 17C to a reverse valve 9. The reverse valve 9 contains a sphere 9C and is connected to the bottom of a water tank 16 by means of an outlet 9A located substantially opposite the connection to the outlet 17C of the three-way valve 17. A conduit 8 having external cooling fins 19 also opens into the reverse valve 9 and the opposite end of the conduit opens out above the water level in the water tank 16.

Furthermore, a branch conduit 20 leads from the outlet conduit 5 between the autoclave and the outlet 17A of the three-way valve 17, to a steam trap 18 which is provided with a drainage conduit 6 which opens out above the water level in the container 16.

The described system operates in the following way:

In order to preheat the autoclave l, the heating means 3 is switched in by way of the thermostat 4 which is set at a temperature corresponding to the sterilization temperature so that the double cleading 2 is heated to this temperature. As soon as this temperature has been reached, the autoclave is ready for use.

In order to carry out the sterilization cycle electrical current is supplied to the heating element 15 in the water container 11, which is at least partially filled with water by means of operating the the thermostat 14 and at the same time the three-way valve 17 is set, preferably also electrically, so that its outlet 17C to the reverse valve 9 is closed, but the outlets 17A and 17B are open. The steam generated in the container 11 now flows through the feeding conduit 13 and the inlet conduit 17 to the autoclave chamber and the air thus forced out of the autoclave chamber is withdrawn through the outlet conduit 5, branch conduit 20, steam trap 18 and conduit 6. The steam trap 18 is held open in conventional manner for the passage of air but closes automatically if steam endeavours to pass through.

Since the outlets 17A, 17B of the three-way valve are open, any water which has collected at the bottom of the autoclave can flow back to the container 11 through the outlet conduit 5, outlets 17A, 17B and the return conduit 10. As soon as the predetermined temperature has been reached in the container 11, the thermostat cuts off the current supply to the element 14, which is however switched on again when the temperature falls below the value set. This occurs repeatedly during the predetermined sterilization time.

At the end of the sterilization process the current supply to the means 15 and the three-way valve 17 may be cut off by means of a timer, for example, which at the same time switches on the heating means 3 in the double cleading 2 via the thermostat 4 so that the autoclave is immediately preheated for the next sterilization cycle. Due to the function of the three-way valve 17, the outlets 17B, 17C are now open whereas the outlet 17A is closed. Steam thus flows from the autoclave 1 through the conduits 7, 13, the container 11 and the conduits l0, 8, back to the water tank 16 since, because of the overpressure now prevailing in the reverse valve 9, its outlet 9A is kept closed. As soon as pressure equalization has been reached, the sphere 9C falls due to its own weight and thus frees the outlet 9A. Water then flows from the tank 16 through the outlet 9A, reverse valve 9, outlet 17B of the three-way valve 17 and the conduit 10 to the container 11 and replaces the water consumed during the sterilization process. In the meanwhile the autoclave is preheated for the next sterilization cycle and the heat thus achieved is simultaneously used to dry the objects in the autoclave sterilized by the sterilization cycle just completed.

The heating block may be made partly of aluminium or some other suitable material and the alternate switching between the heating means 3 and 15 may of course also be performed by hand or by means of other automatic devices than the timer proposed above. Of course, a plurality of heating elements may also be used.

What I claim is:

l. A steam operated sterilization system having a circulating steam phase comprising an autoclave having an interior heating space therein; a water container located exteriorly of the autoclave for producing steam and connected to communicate with the interior of the autoclave; a water storage means connected to the water container; cleading at least partially surrounding said autoclave and a first heating means for heating said cleading; a second heating means for producing steam in the water container; means for selective operation of said first and second heating means before, during or after a sterilization cycle, whereby the first heating means is operated immediately before and after sterilization of articles in the autoclave and the second heating means is operated only during sterilization; the connection between the water container and the interior of the autoclave comprising a steam conduit extending between the container and a steam inlet opening in the upper part of the autoclave, and a branch conduit for return of excess water being arranged between said steam conduit and said water tank.

2. A steam operated sterilization system having a circulating steam phase comprising an autoclave having an interior heating space therein; a water container located exteriorly of the autoclave for producing steam and connected to communicate with the interior of the autoclave; a water storage means connected to the water container; cleading at least partially surrounding said autoclave and a first heating means for heting said cleading; a second heating means for producing steam in the water container; means for selective operation of said first and second heating means before, during or after a sterilization cycle, whereby the first heating means is operated immediately before and after sterilization of articles in the authoclave and the second heating means is operated only during sterilization; a three-way valve being interposed in an outlet conduit between the autoclave and the water container for expelling air and steam from the autoclave, a branch conduit leading to a steam trap being connected to said outlet conduit at a location between the autoclave and the three-way valve.

3. A steam operated sterilization system according to claim 2 in which a first outlet of the three-way valve is connected to the outlet of the outlet conduit; a second outlet of the three-way valve is connected to a return conduitjoined to the water container and the third outlet of the three-way valve is connected to a reverse valve joined to the water storage means for automatic compensation of water losses after each sterilization.

4. A steam operated sterilization system according to claim 3 in which the reverse valve comprises a spherical blocking member and in which a conduit having external cooling fins is connected to the reverse valve and extending above the water level of the water storage 

1. A steam operated sterilization system having a circulating steam phase comprising an autoclave having an interior heating space therein; a water container located exteriorly of the autoclave for producing steam and connected to communicate with the interior of the autoclave; a water storage means connected to the water container; cleading at least partially surrounding said autoclave and a first heating means for heating said cleading; a second heating means for producing steam in the water container; means for selective operation of said first and second heating means before, during or after a sterilization cycle, whereby the first heating means is operated immediately before and after sterilization of articles in the autoclave and the second heating means is operated only during sterilization; the connection between the water container and the interior of the autoclave comprising a steam conduit extending between the container and a steam inlet opening in the upper part of the autoclave, and a branch conduit for return of excess water being arranged between said steam conduit and said water tank.
 2. A steam operated sterilization system having a circulating steam phase comprising an autoclave having an interior heating space therein; a water container located exteriorly of the autoclave for producing steam and connected to communicate with the interior of the autoclave; a water storage means connected to the water container; cleading at least partially surrounding said autoclave and a first heating means for heting said cleading; a second heating means for producing steam in the water container; means for selective operation of said first and second heating means before, during or after a sterilization cycle, whereby the first heating means is operated immediately before anD after sterilization of articles in the authoclave and the second heating means is operated only during sterilization; a three-way valve being interposed in an outlet conduit between the autoclave and the water container for expelling air and steam from the autoclave, a branch conduit leading to a steam trap being connected to said outlet conduit at a location between the autoclave and the three-way valve.
 3. A steam operated sterilization system according to claim 2 in which a first outlet of the three-way valve is connected to the outlet of the outlet conduit; a second outlet of the three-way valve is connected to a return conduit joined to the water container and the third outlet of the three-way valve is connected to a reverse valve joined to the water storage means for automatic compensation of water losses after each sterilization.
 4. A steam operated sterilization system according to claim 3 in which the reverse valve comprises a spherical blocking member and in which a conduit having external cooling fins is connected to the reverse valve and extending above the water level of the water storage means. 